Sulfur dioxide removal prom stack gases

ABSTRACT

SULFUR OXIDES CAN BE REMOVED FROM WASTE GASES BY ABSORPTION IN AMMONIACAL SOLUTION FORMING AMMONIUM BISULFITE, AMMONIUM SULFITE, AND, UNAVOIDABLY, AMMONIUM SULFATE. THE ABSORBER EFFLUENT SOLUTION MAY BE TREATED WITH AMMONIUM BISULFATE TO FORM AMMONIUM SULFATE AND TO RELEASE A CONCENTRATION STREAM OF SO2 SUITABLE FOR CONVERSION TO H2SO4 OR ELEMENTAL SULFUR. AMMONIUM SULFATE MAY BE CRYSTALLIZED FROM THE SOLUTION AND THERMALLY DECOMPOSED TO AMMONIA FOR RECYCLE TO THE ABSORBER AND AMMONIUM BISULFATE FOR RECYCLE TO THE SO2 RELEASE STEP. THE ECONOMICS OF THE PROCESS ARE IMPROVED BY OPERATING THE ABSORBER WITH AN AMMONIACAL SOLUTION HAVING A HIGH CONTENT OF AMMONIUM SULFATE, SUBSEQUENT TREATMENT OF THE SCRUBBER EFFLUENT WITH AMMONIUM BISULFATE AND, AFTER SO2 RELEASE, WITH AMMONIA CAUSES PRECIPITATION OF AMMONIUM SULFATE WITHOUT EVAPORATION OF THE LARGE AMOUNTS OF WATER REQUIRED IN EARLIER CONCEPTS OF THIS PROCESS

UNITED STATES PATENT OFFICE Published at the request of the applicant or owner in accordance with the Notice of Dec. 16, 1969, 869 GB. 687. The abstracts of Defensive Publication applications are identified by distinctly numbered series and are arranged chronologically. The heading of each abstract indicates the number of pages of specification, including claims and sheets of drawings contained in the application as originally filed. The files of these applications are available to the public for inspection and reproduction may be purchased for 30 cents a sheet.

Defensive Publication applications have not been examined as to the merits of alleged invention. The Patent Oflice makes no assertion as to the novelty of the disclosed subject matter.

PUBLISHED APRIL 17, 1973 T909,017 SULFUR DIOXIDE REMOVAL FROM STACK GASES John E. Jordan, 1306 30th St., Sheffield, Ala. 35660,

and George M. Newcombe, 200 Seven Oaks Road,

Apt. 8G, Durham, N.C. 27704 Filed Apr. 13, 1972, Ser. No. 243,636 Int. Cl. C01b 17/00 US. Cl. 423-442 3 Sheets Drawing. 18 Pages Specification Sulfur oxides can be removed from waste gases by ab sorption in ammoniacal solution forming ammonium bisulfite, ammonium sulfite, and, unavoidably, ammonium sulfate. The absorber effiucnt solution may be treated with ammonium bisulfatc to form ammonium sulfate and to release a concentrated stream of S0 suitable for conversion to H 80 or elemental sulfur. Ammonium sulfate may be crystallized from the solution and thermally decomposed to ammonia for recycle to the absorber and ammonium bisulfate for recycle to the S0 release step. The economics of the process are improved by operating the absorber with an ammoniacal solution having a high content of ammonium sulfate; subsequent treatment of the scrubber efiluent with ammonium bisulfate and, after S0 release, with ammonia causes precipitation of ammonium sulfate without evaporation of the large amounts of water required in earlier concepts of this process.

P 17, J. E. JORDON ET AL SULFUR DIOXIDE RFMOVAI; FROM STACK GASES Filed April 13, 1972 m 2 6m mo Emfiw 2 MW mwmmpmom 2 6w 2 K 3 w o SI & $92525 22 $3 

